1. Field of Invention
The present invention relates to a differential pressure gauge.
2. Description of Related Arts
Mechanical differential pressure gauge is an elastic pressure gauge which makes use of easy and frictionless magnetic spiral movement and measures by the rubber diaphragm as the sensing element. When the differential pressure (including positive and negative pressure) acts on the diaphragm, the diaphragm will be out of shape to displace the center thereof. Connector drives the leaf spring which has the magnetic steel to move. Under the magnetic induction, the helix, which has the pointer thereon, will turn around so that the pointer will indicate the pressure value to achieve the aim of measurement.
FIGS. 1 and 2 show a conventional differential pressure gauge whose housing 3 is round. Its helix 6 uses the independent bracket. The central axis of the measuring diaphragm 4 and the leaf spring 1 are connected by the double end stud and a small compression spring. The range adjustment of the conventional differential pressure gauge makes use of the C-shaped clip 2 on the leaf spring. The displacement of the C-shaped clip on the leaf spring will affect the length of the cantilever of the leaf spring to affect the rigidity of the leaf spring so that the range of the differential pressure gauge will change. The measuring diaphragm 4 is connected with the leaf spring 1 which has the magnetic steel 5 by the connector. When the differential pressure acts on the measuring diaphragm 4, the diaphragm 4 will be out of shape to displace its center. With the movement of the leaf spring 1 which has the magnetic steel 5 thereon, the helix 6 will turn around under the magnetic induction so that the pointer can indicate the pressure value.
Under the existing technology to produce the traditional differential pressure gauge, the bracket of the independent helix will incline while zero adjustment. This will affect the measuring accuracy of the differential pressure gauge. Its connection of the diaphragm's central axis and the leaf spring will affect the movement of the diaphragm so that it can not be reacted correctly. It will affect the measuring accuracy of the differential pressure gauge. Its way to adjust the range is complex and the adjusting point is inside of the differential pressure gauge. After the differential pressure gauge has been used for some time, it needs to be re-calibrated. Users can not calibrate it themselves, so users need to send the gauge back to factory. It's troublesome.